Spring Cloud provides tools for developers to quickly build some of the common patterns in distributed systems (e.g. configuration management, service discovery, circuit breakers, intelligent routing, micro-proxy, control bus, one-time tokens, global locks, leadership election, distributed sessions, cluster state). Coordination of distributed systems leads to boiler plate patterns, and using Spring Cloud developers can quickly stand up services and applications that implement those patterns. They will work well in any distributed environment, including the developer’s own laptop, bare metal data centres, and managed platforms such as Cloud Foundry.
Features
Spring Cloud focuses on providing good out of box experience for typical use cases and extensibility mechanism to cover others.
Distributed/versioned configuration
Service registration and discovery
Routing
Service-to-service calls
Load balancing
Circuit Breakers
Global locks
Leadership election and cluster state
Distributed messaging
Spring Cloud takes a very declarative approach, and often you get a lot of features with just a classpath change and/or an annotation. Example application that is a discovery client:
@SpringBootApplication
@EnableDiscoveryClient
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
Main Projects
Spring Cloud Config
Centralized external configuration management backed by a git repository. The configuration resources map directly to Spring Environment but could be used by non-Spring applications if desired.
Spring Cloud Netflix
Integration with various Netflix OSS components (Eureka, Hystrix, Zuul, Archaius, etc.).
Spring Cloud Bus
An event bus for linking services and service instances together with distributed messaging. Useful for propagating state changes across a cluster (e.g. config change events).
Spring Cloud Cloudfoundry
Integrates your application with Pivotal Cloud Foundry. Provides a service discovery implementation and also makes it easy to implement SSO and OAuth2 protected resources.
Spring Cloud Open Service Broker
Provides a starting point for building a service broker that implements the Open Service Broker API.
Spring Cloud Cluster
Leadership election and common stateful patterns with an abstraction and implementation for Zookeeper, Redis, Hazelcast, Consul.
Spring Cloud Consul
Service discovery and configuration management with Hashicorp Consul.
Spring Cloud Security
Provides support for load-balanced OAuth2 rest client and authentication header relays in a Zuul proxy.
Spring Cloud Sleuth
Distributed tracing for Spring Cloud applications, compatible with Zipkin, HTrace and log-based (e.g. ELK) tracing.
Spring Cloud Data Flow
A cloud-native orchestration service for composable microservice applications on modern runtimes. Easy-to-use DSL, drag-and-drop GUI, and REST-APIs together simplifies the overall orchestration of microservice based data pipelines.
Spring Cloud Stream
A lightweight event-driven microservices framework to quickly build applications that can connect to external systems. Simple declarative model to send and receive messages using Apache Kafka or RabbitMQ between Spring Boot apps.
Spring Cloud Stream App Starters
Spring Cloud Stream App Starters are Spring Boot based Spring Integration applications that provide integration with external systems.
Spring Cloud Task
A short-lived microservices framework to quickly build applications that perform finite amounts of data processing. Simple declarative for adding both functional and non-functional features to Spring Boot apps.
Spring Cloud Task App Starters
Spring Cloud Task App Starters are Spring Boot applications that may be any process including Spring Batch jobs that do not run forever, and they end/stop after a finite period of data processing.
Spring Cloud Zookeeper
Service discovery and configuration management with Apache Zookeeper.
Spring Cloud Connectors
Makes it easy for PaaS applications in a variety of platforms to connect to backend services like databases and message brokers (the project formerly known as “Spring Cloud”).
Spring Cloud Starters
Spring Boot-style starter projects to ease dependency management for consumers of Spring Cloud. (Discontinued as a project and merged with the other projects after Angel.SR2.)
Spring Cloud CLI
Spring Boot CLI plugin for creating Spring Cloud component applications quickly in Groovy
Spring Cloud Contract
Spring Cloud Contract is an umbrella project holding solutions that help users in successfully implementing the Consumer Driven Contracts approach.
Spring Cloud Gateway
Spring Cloud Gateway is an intelligent and programmable router based on Project Reactor.
Spring Cloud OpenFeign
Spring Cloud OpenFeign provides integrations for Spring Boot apps through autoconfiguration and binding to the Spring Environment and other Spring programming model idioms.
Spring Cloud Pipelines
Spring Cloud Pipelines provides an opinionated deployment pipeline with steps to ensure that your application can be deployed in zero downtime fashion and easilly rolled back of something goes wrong.
Spring Cloud Function
Spring Cloud Function promotes the implementation of business logic via functions. It supports a uniform programming model across serverless providers, as well as the ability to run standalone (locally or in a PaaS).
Release Trains
Spring Cloud is an umbrella project consisting of independent projects with, in principle, different release cadences. To manage the portfolio a BOM (Bill of Materials) is published with a curated set of dependencies on the individual project (see below). The release trains have names, not versions, to avoid confusion with the sub-projects. The names are an alphabetic sequence (so you can sort them chronologically) with names of London Tube stations (“Angel” is the first release, “Brixton” is the second). When point releases of the individual projects accumulate to a critical mass, or if there is a critical bug in one of them that needs to be available to everyone, the release train will push out “service releases” with names ending “.SRX”, where “X” is a number.
Table 1. Release train Spring Boot compatibility Release Train Boot Version
Hoxton
2.2.x
Greenwich
2.1.x
Finchley
2.0.x
Edgware
1.5.x
Dalston
1.5.x
Greenwich builds and works with Spring Boot 2.1.x, and is not expected to work with Spring Boot 1.5.x.
Note: The Dalston release train will reach end-of-life in December 2018. Edgware will follow the end-of-life cycle of Spring Boot 1.5.x.
The Dalston and Edgware release trains build on Spring Boot 1.5.x, and are not expected to work with Spring Boot 2.0.x.
The Camden release train was marked end-of-life.
The Camden release train builds on Spring Boot 1.4.x, but is also tested with 1.5.x.
The Brixton and Angel release trains were marked end-of-life (EOL) in July 2017.
The Brixton release train builds on Spring Boot 1.3.x, but is also tested with 1.4.x.
The Angel release train builds on Spring Boot 1.2.x, and is incompatible in some areas with Spring Boot 1.3.x. Brixton builds on Spring Boot 1.3.x and is similarly incompatible with 1.2.x. Some libraries and most apps built on Angel will run fine on Brixton, but changes will be required anywhere that the OAuth2 features from spring-cloud-security 1.0.x are used (they were mostly moved to Spring Boot in 1.3.0).
Use your dependency management tools to control the version. If you are using Maven remember that the first version declared wins, so declare the BOMs in order, with the first one usually being the most recent (e.g. if you want to use Spring Boot 1.3.6 with Brixton.RELEASE, put the Boot BOM first). The same rule applies to Gradle if you use the Spring dependency management plugin.
The release train contains a spring-cloud-dependencies as well as the spring-cloud-starter-parent. You can use the parent as you would the spring-boot-starter-parent (if you are using Maven). If you only need dependency management, the “dependencies” version is a BOM-only version of the same thing (it just contains dependency management and no plugin declarations or direct references to Spring or Spring Boot). If you are using the Spring Boot parent POM, then you can use the BOM from Spring Cloud. The opposite is not true: using the Cloud parent makes it impossible, or at least unreliable, to also use the Boot BOM to change the version of Spring Boot and its dependencies.
Talks and Videos
Beginner’s Guide To Spring Cloud
Quick start
Bootstrap your application with Spring Initializr.
